YinHoNg sounds like a driver problem make sure you have updated your drivers. What os? If xp have you installed sp2? I had a similar fault problem turned out to be that my graphics card was faulty. It can slo be your BIOS needs flashed, keep bumping your thread and you will get some good advice to follow. click here some info on this may help as well
The computer is not restarting so much now, but freezing a lot. i'm thinking about reinstalling windows again but don't know if this will be worth it. i've already done it once already and it hasnt made a big difference.
RIVA is fr the 128 128ZX so you want the TN2 driver as for BIOS flash, by the tone of your questioning (in that you do not seem to sure) I would leave the BIOS flash to someone with better knowledge in this area as you could end up with a puter that does not work